This invention relates, in general, to electronic components, and more particularly, to apparatuses used to manufacture integrated circuits.
Sputtering deposition tools have been used since at least the early 1970's to deposit films of material onto semiconductor substrates in the fabrication of electronic components. Conventional sputtering equipment has a reaction chamber containing a sputtering target over a semiconductor substrate, both of which are between a pair of electrodes. The reaction chamber is pumped to a vacuum and a plasma ignitor is used to excite gas molecules near the plasma ignitor, which helps ignite the plasma in the reaction chamber. The plasma is then used to direct ions towards the semiconductor substrate in an etch application or towards the sputtering target in a deposition application.
Conventional ignitors have a single filament that helps ignite the plasma by emitting thermal excitation when active. However, in order to effectively ignite the plasma, the filament is placed in relatively close proximity to the sputtering target, the etch platform, or the semiconductor substrate. Therefore, the filament can be partially exposed to the harsh plasma environment. Consequently, the filament becomes brittle while active and is frequently damaged during the operation of a sputtering tool. The average operational lifetime of a filament depends in part on the type of material used to make the target, the number of wafers processed with the equipment, and the location of the filament in the reaction chamber.
When the filament breaks, the sputtering tool is inoperable and must be disabled to replace the filament. This operation can take on average from 12 to 24 hours, during which time no processing of semiconductor substrates can occur. The solution proposed by the manufacturers of sputtering equipment calls for preventative maintenance that replaces the filament at fixed intervals which are theoretically shorter than the expected lifetime of the filament. However, this solution is not a complete solution because it only removes the "unpredictability" of replacing the filaments. The throughput of the sputtering tool is still limited by the time it takes to replace the filament.
Accordingly, there is a long felt need to provide a plasma ignitor that did not have to be replaced as frequently as conventional ignitors, and consequently, increased the up-time and throughput of semiconductor manufacturing tools. In addition, it would also be advantageous if the ignitor could provide semiconductor equipment that has a more predictable preventative maintenance schedule and that could be used for other applications in the semiconductor industry.